Solid electrolytic capacitor and method for manufacturing same

ABSTRACT

A solid electrolytic capacitor includes a capacitor element. The capacitor element includes an anode foil including a base material part and a porous part disposed on a surface of the base material part, a dielectric layer disposed on at least a part of a surface of the anode foil, a solid electrolyte layer covering at least a part of the dielectric layer, and a cathode lead-out layer covering at least a part of the solid electrolyte layer. The anode foil includes an anode section on which the solid electrolyte layer is not disposed, a cathode formation section on which the solid electrolyte layer is disposed, and a separation section located between the anode section and the cathode formation section. A first insulating material is disposed on a surface of the porous part in the separation section. And at least a part of a region of the porous part that is covered with the first insulating material includes a second insulating material.

TECHNICAL FIELD

The present disclosure relates to a solid electrolytic capacitor and amethod for manufacturing the same.

BACKGROUND

A solid electrolytic capacitor includes a capacitor element including asolid electrolyte layer, an electrode terminal electrically connected tothe capacitor element, and an exterior body sealing the capacitorelement. The capacitor element includes, for example, an anode foilhaving a porous part in a surface layer thereof, a dielectric layerdisposed on at least a part of a surface of the anode foil, a solidelectrolyte layer covering at least a part of the dielectric layer, anda cathode lead-out layer covering at least a part of the solidelectrolyte layer.

Unexamined Japanese Patent Publication No. 2007-165777 proposes a solidelectrolytic capacitor including a plurality of capacitor elements eachincluding an anode part made of a valve metal with an oxide film layerdisposed on a surface thereof, a cathode part including a solidelectrolyte layer in a predetermined region of the surface, which has alayered shape including an outermost layer made of a conductivematerial, and a resist part electrically insulating the anode part andthe cathode part.

International Publication WO 2007/061005 proposes a solid electrolyticcapacitor including a shielding layer in a region separating an anodepart region and a cathode part region of a substrate that has a porouslayer thereon and is used for the solid electrolytic capacitor.

International Publication WO 2000/067267 proposes a method formanufacturing a solid electrolytic capacitor. The method includes a stepof applying a masking material solution for forming a masking layer in apermeation part of a dielectric film into which the masking materialsolution penetrates.

Unexamined Japanese Patent Publication No. 2007-305661 proposes that aresist layer is provided on an etching layer formed on a surface of avalve metal for preventing penetration of a solid electrolyte materialto separate an anode part and a cathode part. A first groove is formedin a region close to the cathode part, and a second groove is formed ina region closer to the anode part than the first groove. And the resistlayer is formed in the second groove.

SUMMARY

In the solid electrolytic capacitor, air may enter through the porouspart of the anode foil connected to the electrode terminal. When oxygenin the air having entered comes into contact with the solid electrolytelayer included in the capacitor element, the conductive polymer includedin the solid electrolyte layer may be deteriorated under hightemperature, and the capacitance of the solid electrolytic capacitor maybe reduced.

A first aspect of the present disclosure relates to a solid electrolyticcapacitor including a capacitor element. The capacitor element includesan anode foil including a base material part and a porous part disposedon a surface of the base material part, a dielectric layer disposed onat least a part of a surface of the anode foil, a solid electrolytelayer covering at least a part of the dielectric layer, and a cathodelead-out layer covering at least a part of the solid electrolyte layer.The anode foil includes an anode section on which the solid electrolytelayer is not disposed, a cathode formation section on which the solidelectrolyte layer is disposed, and a separation section located betweenthe anode section and the cathode formation section. A first insulatingmaterial is disposed on a surface of the porous part in the separationsection. At least a part of a first region of the porous part, which iscovered with the first insulating material, includes a second insulatingmaterial.

A second aspect of the present disclosure relates to a solidelectrolytic capacitor including a capacitor element. The capacitorelement includes an anode foil including a base material part and aporous part disposed on a surface of the base material part, adielectric layer disposed on a surface of the anode foil, a solidelectrolyte layer covering at least a part of the dielectric layer, anda cathode lead-out layer covering at least a part of the solidelectrolyte layer. The anode foil includes an anode section on which thesolid electrolyte layer is not disposed, a cathode formation section onwhich the solid electrolyte layer is disposed, and a separation sectionlocated between the anode section and the cathode formation section. Afirst insulating material is disposed on or included in at least a partof the separation section. The capacitor element further includes asecond insulating material in at least a part of a region of theseparation section, which is located closer to the anode section thanthe first insulating material.

A third aspect of the present disclosure relates to a solid electrolyticcapacitor including a capacitor element. The capacitor element includesan anode foil including a base material part and a porous part disposedon a surface of the base material part, a dielectric layer disposed on asurface of the anode foil, a solid electrolyte layer covering at least apart of the dielectric layer, and a cathode lead-out layer covering atleast a part of the solid electrolyte layer. The anode foil includes ananode section on which the solid electrolyte layer is not disposed, acathode formation section on which the solid electrolyte layer isdisposed, and a separation section located between the anode section andthe cathode formation section. A first insulating material is disposedon or included in at least a part of the separation section. The solidelectrolyte layer covers at least a part of a region of the separationsection, which is located closer to the cathode formation section thanthe first insulating material.

A fourth aspect of the present disclosure relates to a solidelectrolytic capacitor including a capacitor element. The capacitorelement includes an anode foil including a base material part and aporous part disposed on a surface of the base material part, adielectric layer disposed on a surface of the anode foil, a solidelectrolyte layer covering at least a part of the dielectric layer, anda cathode lead-out layer covering at least a part of the solidelectrolyte layer. The anode foil includes an anode section on which thesolid electrolyte layer is not disposed, a cathode formation section onwhich the solid electrolyte layer is disposed, and a separation sectionlocated between the anode section and the cathode formation section. Afirst insulating material is disposed on or included in at least a partof the separation section. A second groove is formed to be adjacent tothe first insulating material at a side close to the cathode formationsection side in the separation section. The solid electrolyte layer isdisposed in at least a part of the second groove.

A fifth aspect of the present disclosure relates to a solid electrolyticcapacitor including a capacitor element. The capacitor element includesan anode foil including a base material part and a porous part disposedon a surface of the base material part, a dielectric layer disposed on asurface of the anode foil, a solid electrolyte layer covering at least apart of the dielectric layer, and a cathode lead-out layer covering atleast a part of the solid electrolyte layer. The anode foil includes ananode section on which the solid electrolyte layer is not disposed, acathode formation section on which the solid electrolyte layer isdisposed, and a separation section located between the anode section andthe cathode formation section. A first insulating material is disposedon or included in at least a part of the separation section. A thirdgroove is formed in at least a part of the cathode formation section.The solid electrolyte layer is disposed in at least a part of the thirdgroove.

A sixth aspect of the present disclosure relates to a solid electrolyticcapacitor including a capacitor element. The capacitor element includesan anode foil including a base material part and a porous part disposedon a surface of the base material part, a dielectric layer disposed on asurface of the anode foil, a solid electrolyte layer covering at least apart of the dielectric layer, and a cathode lead-out layer covering atleast a part of the solid electrolyte layer. The anode foil includes ananode section on which the solid electrolyte layer is not disposed, acathode formation section on which the solid electrolyte layer isdisposed, and a separation section located between the anode section andthe cathode formation section. A first insulating material is disposedon or included in at least a part of the separation section. A secondgroove is formed to be adjacent to the first insulating material at aside close to the cathode formation section side in the separationsection. A second insulating material is disposed in at least a part ofthe second groove.

A seventh aspect of the present disclosure relates to a method formanufacturing a solid electrolytic capacitor. The method includes:

(i) forming a dielectric layer on at least a part of a surface of ananode foil, the anode foil including a base material part and a porouspart disposed on a surface of the base material part;

(ii) compressing or partially removing, after defining an anode section,a cathode formation section, and a separation section located betweenthe anode section and the cathode formation section in the anode foil onwhich the dielectric layer is formed, the porous part in the separationsection;

(iii) disposing a first insulating material on a surface of theseparation section;

(iv) covering at least a part of the dielectric layer in the cathodeformation section with a solid electrolyte layer;

(v) covering at least a part of the solid electrolyte layer with acathode lead-out layer; and

(vi) after step (v), impregnating the porous part in at least a part ofa region of the separation section with a second insulating material,the region of the separation section being covered with the firstinsulating material.

An eighth aspect of the present disclosure relates to a method formanufacturing a solid electrolytic capacitor. The method includes:

(i) forming a dielectric layer on at least a part of a surface of ananode foil, the anode foil including a base material part and a porouspart disposed on a surface of the base material part;

(ii) conducting at least one of compression or removal of, afterdefining an anode section, a cathode formation section, and a separationsection between the anode section and the cathode formation section inthe anode foil on which the dielectric layer is formed, at least a partof the porous part in the separation section;

(iii) disposing a first insulating material in at least a part of theseparation section or impregnating at least a part of the separationsection with a first insulating material;

(iv) covering at least a part of the dielectric layer in the cathodeformation section with a solid electrolyte layer;

(v) covering at least a part of the solid electrolyte layer with acathode lead-out layer; and

(vi) after step (v), disposing a second insulating material in at leasta part of a region of the separation section or impregnating the atleast a part of the region of the separation section with the secondinsulating material, the region of the separation section being locatedcloser to the anode section than the first insulating material.

According to the present disclosure, a decrease in capacitance of thesolid electrolytic capacitor can be suppressed after being exposed to ahigh temperature environment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating a solidelectrolytic capacitor according to a first exemplary embodiment of thepresent disclosure.

FIG. 2 is a cross-sectional view schematically illustrating a capacitorelement included in the solid electrolytic capacitor of FIG. 1 .

FIG. 3 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a secondexemplary embodiment of the present disclosure.

FIG. 4 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a thirdexemplary embodiment of the present disclosure.

FIG. 5 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a fourthexemplary embodiment of the present disclosure.

FIG. 6 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a fifthexemplary embodiment of the present disclosure.

FIG. 7 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a sixthexemplary embodiment of the present disclosure.

FIG. 8 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to aseventh exemplary embodiment of the present disclosure.

FIG. 9 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to aneighth exemplary embodiment of the present disclosure.

FIG. 10 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a ninthexemplary embodiment of the present disclosure.

FIG. 11 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a tenthexemplary embodiment of the present disclosure.

FIG. 12 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to aneleventh exemplary embodiment of the present disclosure.

FIG. 13 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to atwelfth exemplary embodiment of the present disclosure.

FIG. 14 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to athirteenth exemplary embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Novel features of the present disclosure are set forth in the appendedclaims. Meanwhile both construction and content of the presentdisclosure will be better understood by the following detaileddescription with the drawings, taken in conjunction with otherobjectives and features of the present disclosure.

An anode foil of a capacitor element includes a porous part disposed ona surface of a base material part. The porous part includes many voids.In the anode section of the anode foil on which the solid electrolytelayer is not disposed, the electrode terminal is connected. Air mayenter into the capacitor element from the electrode terminal sidethrough the voids of the porous part, and thus the conductive polymerincluded in the solid electrolyte layer may be deteriorated. Suchdeterioration of the conductive polymer is remarkable particularly in ahigh-temperature environment.

In the solid electrolytic capacitor according to the first aspect of thepresent disclosure, the separation section is disposed between the anodesection and the cathode formation section in the anode foil of thecapacitor element, and the first insulating material is disposed on asurface of the porous part in the separation section. Note that in theseparation section, a region where the first insulating material isdisposed is defined as a first region, a region between the firstinsulating material (or first region) and the cathode formation sectionis defined as a second region, and a region closer to the anode sectionthan the first insulating material (or first region) is defined as athird region. In the solid electrolytic capacitor, at least a part ofthe first region of the porous part, which is covered with the firstinsulating material, includes the second insulating material. Since theporous part of the first region includes the second insulating material,entry of air through the first region into the capacitor element issuppressed.

The solid electrolytic capacitor according to the above aspect can beformed by impregnating voids of the porous part in the first region withthe second insulating material after forming a capacitor element inwhich the first insulating material is disposed on a surface of theseparation section. From the viewpoint of enhancing the effect ofsuppressing the entry of air, the porous part (more specifically, voidsof porous part) of the first region may be filled with the secondinsulating material.

The solid electrolytic capacitor according to the second aspect of thepresent disclosure includes the separation section located between theanode section and the cathode formation section in the anode foil of thecapacitor element. A first insulating material is disposed on orincluded in at least a part of the separation section. The capacitorelement includes a second insulating material in at least a part of aregion (third region) that is closer to the anode section than the firstinsulating material in the separation section. As a result, it ispossible to suppress entry of air into the capacitor element from theanode section side.

The solid electrolytic capacitor according to the second aspect can bemanufactured by compressing and/or removing at least a part of theporous part of the separation section, disposing the first insulatingmaterial in at least a part of the separation section or impregnatingthe at least a part of the separation section with the first insulatingmaterial, forming the solid electrolyte layer and the cathode lead-outlayer, and then disposing the second insulating material in separationsection or impregnating the separation section with the secondinsulating material. The second insulating material is disposed in orused to impregnate at least a part of the third region.

In the solid electrolytic capacitor according to the third aspect of thepresent disclosure, the first insulating material is disposed on orincluded in at least a part of the separation section, and at least apart of a region (i.e., second region of separation unit) of theseparation section that is closer to the cathode formation section thanthe first insulating material (or first region) is covered with thesolid electrolyte layer. Additionally, in the solid electrolyticcapacitor according to the fourth aspect of the present disclosure, thefirst insulating material is disposed on or included in at least a partof the separation section, the second groove is formed to be adjacent tothe first insulating material at a side close to the cathode formationsection in the separation section, and the solid electrolyte layer isdisposed in at least a part of the second groove. The second groove isformed in the second region. In these solid electrolytic capacitors,since the solid electrolyte layer is disposed in at least a part of thesecond region, entry of air through the second region is suppressed.From the viewpoint of enhancing the effect of suppressing the entry ofair, the second groove may be filled with the solid electrolyte layer.

In the solid electrolytic capacitor according to the fifth aspect of thepresent disclosure, the first insulating material is disposed on orincluded in at least a part of the separation section, the third grooveis formed in at least a part of the cathode formation section, and thesolid electrolyte layer is disposed in at least a part of the thirdgroove. In such a solid electrolytic capacitor, entry of air through aregion located closer to the anode section than the third groove issuppressed. From the viewpoint of enhancing the effect of suppressingthe entry of air, the third groove may be filled with the solidelectrolyte layer.

In the solid electrolytic capacitor according to the sixth aspect of thepresent disclosure, the first insulating material is disposed on orincluded in at least a part of the separation section, the second grooveis formed to to be adjacent to the first insulating material at a sideclose to the cathode formation section in the separation section, andthe second insulating material is disposed in at least a part of thesecond groove. The second groove is formed in the second region. In sucha solid electrolytic capacitor, since the second insulating material isdisposed in at least a part of the second region, entry of air throughthe second region is suppressed. From the viewpoint of enhancing theeffect of suppressing the entry of air, the second groove may be filledwith the second insulating material.

As described above, with the solid electrolytic capacitors of theseaspects, entry of air into the capacitor element is suppressed. Thisincreases the effect of suppressing degradation of the conductivepolymer included in the solid electrolyte layer even after the solidelectrolytic capacitor is exposed to a high temperature environment.Hence, a decrease in capacitance after the heat resistance test can besuppressed. Additionally, since the heat resistance of the solidelectrolyte layer is improved, an increase in equivalent seriesresistance (ESR) and dielectric loss tangent (tan δ) after the heatresistance test can be reduced.

Note that the phrase “the porous part, the separation section, thecapacitor element, or the like includes the insulating material” is usedin a broad sense including a case where the porous part, the separationsection, or the capacitor element (more specifically, voids thereof) isimpregnated with the insulating material and a case where the porouspart, the separation section, or the capacitor element is filled withthe insulating material.

Hereinafter, a solid electrolytic capacitor according to the aboveaspects of the present disclosure and a method for manufacturing thesame will be described more specifically with reference to the drawingsas necessary.

[Solid Electrolytic Capacitor]

(Capacitor Element)

A capacitor element included in a solid electrolytic capacitor includesan anode foil, a dielectric layer formed on at least a part of a surfaceof the anode foil, a solid electrolyte layer covering at least a part ofthe dielectric layer, and a cathode lead-out layer covering at least apart of the solid electrolyte layer. The anode foil includes a basematerial part and a porous part disposed on a surface of the basematerial part. Further, the anode foil is defiled into a cathodeformation section in which the solid electrolyte layer is formed, ananode section in which the solid electrolyte layer is not formed, and aseparation section located between the anode section and the cathodeformation section. The separation section may have, for example, a part(thin part) where the thickness of the porous part is small. The thinpart is formed by compressing or partially removing the porous part. Apart obtained by compressing the porous part may be referred to as acompressed part. A recess formed in the separation section bycompressing and/or removing the porous part may be referred to as agroove. The groove may be formed on the base material part with theporous part interposed therebetween. Alternatively, the groove may bedirectly formed on the base material part without the porous partinterposed therebetween. In a part where a groove is formed (or thinpart), the passage of air is reduced as compared with other parts, andthus it is advantageous to provide the groove from the viewpoint ofsuppressing entry of air.

FIG. 1 is a cross-sectional view schematically illustrating a structureof a solid electrolytic capacitor according to a first exemplaryembodiment of the present disclosure. FIG. 2 is an enlargedcross-sectional view schematically illustrating capacitor element 2included in the solid electrolytic capacitor of FIG. 1 .

Solid electrolytic capacitor 1 includes capacitor element 2, exteriorbody 3 that seals capacitor element 2, and anode lead terminal 4 andcathode lead terminal 5 each of which is at least partially exposed tothe outside of exterior body 3. Exterior body 3 has a substantiallyrectangular parallelepiped outer shape, and solid electrolytic capacitor1 also has a substantially rectangular parallelepiped outer shape.

Capacitor element 2 includes anode foil 6, a dielectric layer (notshown) covering a surface of anode foil 6, and cathode part 8 coveringthe dielectric layer. The dielectric layer is formed, at minimum, on atleast a part of the surface of anode foil 6.

Cathode part 8 includes solid electrolyte layer 9 and cathode lead-outlayer 10. Solid electrolyte layer 9 is formed so as to cover at least apart of the dielectric layer. Cathode lead-out layer 10 is formed so asto cover at least a part of solid electrolyte layer 9. Cathode lead-outlayer 10 has carbon layer 11 and metal paste layer 12. Cathode leadterminal 5 is electrically connected to cathode part 8 via adhesivelayer 14 made of a conductive adhesive.

Anode foil 6 includes base material part 6 a and porous part 6 b formedon a surface of base material part 6 a. Anode foil 6 has anode section16 a on which solid electrolyte layer 9 is not formed, cathode formationsection 16 b on which solid electrolyte layer 9 (or cathode part 8) isformed, and separation section 16 c located between anode section 16 aand cathode formation section 16 b. Anode lead terminal 4 iselectrically connected to anode section 16 a of anode foil 6 by welding.

First insulating material 13 is disposed on a surface of porous part 6 bin separation section 16 c. First insulating material 13 restricts(electrical) contact between anode section 16 a and cathode part 8 bypreventing the conductive polymer from creeping toward anode section 16a when solid electrolyte layer 9 is formed. In the illustrated example,separation section 16 c has thin part 26, and first insulating material13 is disposed on thin part 26. First insulating material 13 may bedisposed on at least a part of thin part 26. Note that separationsection 16 c does not necessarily have to have thin part 26.

In the present exemplary embodiment, at least a part of a region ofporous part 6 b of first region 36 a covered with first insulatingmaterial 13 includes second insulating material 7. More specifically,porous part 6 b of first region 36 a includes second insulating material7. Porous part 6 b includes voids. Hence, porous part 6 b includessecond insulating material 7 in a state where the voids are impregnatedwith second insulating material 7. Since porous part 6 b of first region36 a includes second insulating material 7, entry of air into thecapacitor element through first region 36 a is suppressed. As a result,deterioration of the conductive polymer included in solid electrolytelayer 9 due to oxygen is suppressed, so that heat resistance of solidelectrolyte layer 9 can be enhanced. A decrease in capacitance of thesolid electrolytic capacitor after the heat resistance test can besuppressed. Additionally, an increase of ESR and a dielectric losstangent after the heat resistance test can be reduced.

Second insulating material 7 is included, at minimum, in at least porouspart 6 b of first region 36 a. Second insulating material 7 may also beincluded at least around first region 36 a. In this case, entry of airinto capacitor element 2 through porous part 6 b around first region 36a is suppressed. Further, second insulating material 7 may be includedin at least a part of cathode lead-out layer 10. From this, it ispossible to suppress entry of air into capacitor element 2 throughcathode lead-out layer 10.

For example, second insulating material 7 may be included in porous part6 b between first insulating material 13 and cathode lead-out layer 10(in other words, porous part 6 b of second region 36 b located betweenfirst insulating material 13 of porous part 6 b and cathode lead-outlayer 10). Further, second insulating material 7 may be included inporous part 6 b of a region located closer to anode section 16 a thanfirst insulating material 13 (in other words, porous part 6 b of thirdregion 36 c located closer to anode section 16 a than first insulatingmaterial 13 of porous part 6 b). In this case, depending on the positionof first insulating material 13, the part including second insulatingmaterial 7 may be located in porous part 6 b of any of anode section 16a or porous part 6 b of separation section 16 c.

Second insulating material 7 may be included at these positions in animpregnated state or in a filled state.

FIG. 3 is a cross-sectional view schematically illustrating capacitorelement 2 included in a solid electrolytic capacitor according to asecond exemplary embodiment. Since cathode part 8 of capacitor element 2includes a plurality of layers and has a thickness to some extent, arecess (neck) is formed between cathode part 8 and separation section 16c (or first insulating material 13). As shown in FIG. 3 , a surface ofthe recess (neck) may be covered with third insulating material 17. Atleast a part of the surface of the recess, at minimum, is covered withthird insulating material 17, and the recess may be filled with thirdinsulating material 17. Third insulating material 17 may adhere to atleast the periphery of first region 36 a. Further, third insulatingmaterial 17 may cover at least a part of at least one of cathodelead-out layer 10 or solid electrolyte layer 9. For example, as shown inFIG. 3 , an end of cathode lead-out layer 10 or an end of solidelectrolyte layer 9 at a side close to anode section 16 a and itsperiphery may be covered with third insulating material 17. Thirdinsulating material 17 may cover at least a part of a surface of solidelectrolyte layer 9 that is not covered with cathode lead-out layer 10.For example, near the end of cathode lead-out layer 10 at a side closeto anode section 16 a, there is a part where solid electrolyte layer 9is not covered with cathode lead-out layer 10. In such a case, at leasta part of solid electrolyte layer 9 may be covered with third insulatingmaterial 17 disposed between first insulating material 13 (or firstregion 36 a) and the end of cathode lead-out layer 10 at a side close toanode section 16 a. In the case of FIG. 3 , as the same in the case ofFIGS. 1 and 2 , second insulating material is included in porous part 6b of first region 36 a, second region 36 b, and third region 36 c.Capacitor element 2 in FIG. 3 is the same as capacitor element 2 in FIG.2 except that at least a part of the recess (neck) and the end ofcathode lead-out layer 10 and/or solid electrolyte layer 9 at a sideclose to anode section 16 a and its periphery is covered with thirdinsulating material 17. Hence, the description of FIGS. 1 and 2 can bereferred to.

Note that although not shown, at least a part of porous part 6 b that islocated closer to anode section 16 a than first insulating material 13may be covered with third insulating material 17.

FIG. 4 is an enlarged cross-sectional view schematically illustratingcapacitor element 2 included in a solid electrolytic capacitor accordingto a third exemplary embodiment.

In FIG. 4 , third insulating material 17 covers a surface of firstinsulating material 13, a surface of porous part 6 b between firstinsulating material 13 and the end of cathode lead-out layer 10 at aside close to anode section 16 a, and a surface of porous part 6 blocated next to first insulating material 13 at a side close to on anodesection 16 a. Further, a second insulating material is also included inporous part 6 b of second region 36 b and third region 36 c.

Since metal paste layer 12 is not dense, voids exist in metal pastelayer 12. Hence, when an insulating material is supplied to a surface ofcathode lead-out layer 10, metal paste layer 12 is impregnated with theinsulating material. The impregnated insulating material corresponds tosecond insulating material 7. In FIG. 4 , entirety of metal paste layer12 is impregnated with second insulating material 7. Note that secondinsulating material 7 does not necessarily have to be included in theentirety of metal paste layer 12, and is included, at minimum, in atleast a part of metal paste layer 12. When metal paste layer 12 includessecond insulating material, it is possible to suppress entry of air intocapacitor element 2 through metal paste layer 12, and it is possible tosuppress a decrease in heat resistance of solid electrolyte layer 9 evenmore. Further, an insulating material may be attached to the surface ofcathode lead-out layer 10. The insulating material covering at least apart of cathode lead-out layer 10 corresponds to third insulatingmaterial 17.

The second insulating material supplied from at least one of separationsection 16 c, anode section 16 a, and cathode lead-out layer 10penetrates into porous part 6 b, so that porous part 6 b in at least oneof first region 36 a, second region 36 b, third region 36 c, and cathodeformation section 16 b is impregnated or filled with the secondinsulating material. The second insulating material supplied to thesurface of cathode lead-out layer 10 may penetrate into cathode lead-outlayer 10, solid electrolyte layer 9, and the like to impregnate or fillporous part 6 b in cathode formation section 16 b.

FIG. 5 is a cross-sectional view schematically illustrating a capacitorelement included in a solid electrolytic capacitor according to a fourthexemplary embodiment. In FIG. 5 , three capacitor elements 102A, 102B,and 102C are laminated. In FIG. 5 , only the laminated body part ofthese capacitor elements is illustrated for the sake of convenience. Theconfiguration of FIG. 5 is different from the configurations of FIGS. 2to 4 in that three capacitor elements are laminated and the regioncovered with an insulating material is different. However, thedescription of FIGS. 1 to 4 can be referred to for the rest of theconfiguration.

In FIG. 5 , each of capacitor elements 102A, 102B, and 102C includesanode foil 6, a dielectric layer covering anode foil 6, solidelectrolyte layer 9 covering the dielectric layer, and cathode lead-outlayer 10 covering solid electrolyte layer 9, as the same in the case ofFIG. 2 . Anode foil 6 is defined into anode section 16 a, cathodeformation section 16 b, and separation section 16 c therebetween. Firstinsulating material 13 is disposed on porous part 6 b of separationsection 16 c.

Fourth insulating material 117 covers a part of a surface of thelaminated body of capacitor elements 102A, 102B, and 102C. Morespecifically, fourth insulating material 117 covers a part of a surfaceof first insulating material 13, porous part 6 b between firstinsulating material 13 and the end of solid electrolyte layer 9 at aside close to anode section 16 a, and a part of a surface of solidelectrolyte layer 9. Fourth insulating material 117 may cover at least apart of cathode lead-out layer 10. Fourth insulating material 117 maycover at least a part of the laminated body. Even in the case of thelaminated body of the capacitor elements, at least a part of the surfaceis covered with fourth insulating material 117, so that entry of airinto each capacitor element is suppressed, and a decrease in heatresistance of solid electrolyte layer 9 can be suppressed. Further,after the laminated body of the capacitor elements is connected to alead frame, at least a part of surfaces of the laminated body and thelead frame may be covered with fourth insulating material 117. Theposition of fourth insulating material 117 in the laminated body is notlimited to these cases. For example, in the laminated body, at least oneof a part between adjacent capacitor elements, between first insulatingmaterials 13 of adjacent capacitor elements, between third insulatingmaterials 17 of adjacent capacitor elements, and the entire surface ofthe laminated body may be covered with fourth insulating material 117.

In the laminated body, at least a part of cathode lead-out layer 10(e.g., silver paste layer) may include a second insulating material. Bysupplying the insulating material to the surface of the laminated body,the insulating material penetrates into porous part 6 b, and the firstregion, the second region, porous part 6 b of cathode formation section16 b, and the like are also impregnated or filled with the insulatingmaterial. The impregnated or filled insulating material corresponds tothe second insulating material. Further, in the laminated body, at leasta part of the periphery of at least first region 36 a, cathode lead-outlayer 10, solid electrolyte layer 9, and the like may be covered with aninsulating material (corresponding to third insulating material).

Although the following exemplary embodiments shown in FIGS. 6 to 14 aredifferent from FIGS. 2 to 4 in that a groove part is formed in an anodesection, or a position of an insulating material, a region covered by asolid electrolyte layer, or the like is different, the description ofFIGS. 1 to 4 can be referred to for the rest of the configuration. Inthese exemplary embodiments, as the same in the case of FIGS. 2 to 4 ,first insulating material 13 is disposed on a surface of porous part 6 b(more specifically, thin part 26). Meanwhile, the present invention isnot limited to such a case. First insulating material 13 may be disposedon at least a part of separation section 16 c or may be included in atleast a part of separation section 16 c. First insulating material 13may be disposed on at least a part of thin part 26. Further, separationsection 16 c does not necessarily have to have thin part 26. Firstinsulating material 13 does not necessarily have to be disposed on thesurface of porous part 6 b, and may be disposed directly on basematerial part 6 a without interposing porous part 6 b. Note that thecapacitor elements shown in these exemplary embodiments may be used asthe capacitor elements forming the laminated body of FIG. 5 .

FIG. 6 is an enlarged cross-sectional view schematically illustratingcapacitor element 2 included in a solid electrolytic capacitor accordingto a fifth exemplary embodiment. In the present exemplary embodiment, inseparation section 16 c, second insulating material 7 is included in atleast a part of third region 36 c that is located closer to anodesection 16 a than first region 36 a where first insulating material 13is disposed. Since second insulating material 7 is included in thirdregion 36 c, entry of air into capacitor element 2 from anode section 16a is suppressed. Second insulating material 7 may be disposed in thirdregion 36 c, and at least a part of third region 36 c may be impregnatedor filled with second insulating material 7.

In the illustrated example, thin part 26 is formed in third region 36 cas well, whereby groove (first groove) 19 is formed adjacent to firstinsulating material 13. First groove 19 is filled with second insulatingmaterial 7. Since second insulating material 7 is included in firstgroove 19 as described above, entry of air into capacitor element 2through porous part 6 b in third region 36 c is suppressed even more.

Second insulating material 7 does not necessarily have to be included soas to fill the entire first groove 19 as shown in FIG. 6 , and secondinsulating material 7 is disposed, at minimum, in at least a part offirst groove 19. For example, second insulating material 7 may bedisposed so as to cover at least a part of first groove 19.Alternatively, first groove 19 may be impregnated with second insulatingmaterial 7. For example, second insulating material 7 may be filled soas to partially fill first groove 19, or second insulating material 7may be disposed on at least a part of an inner surface of first groove19.

Porous part 6 b around first groove 19 may include second insulatingmaterial 7 in an impregnated (or filled) state. It is possible tosuppress entry of air into capacitor element 2 through porous part 6 baround first groove 19. For example, in third region 36 c, porous part 6b existing below first groove 19 may include second insulating material7 in an impregnated (or filled) state. Further, at least a part (such asa part close to third region 36 c) of porous part 6 b in first region 36a may include second insulating material 7 in an impregnated (or filled)state.

Further, at least a part of cathode lead-out layer 10 may include secondinsulating material 7 in an impregnated or filled state. Although notshown, at least a part of cathode lead-out layer 10 may be covered withthird insulating material 17. In at least one of these cases, entry ofair into capacitor element 2 from cathode lead-out layer 10 can besuppressed.

For example, porous part 6 b between first insulating material 13 andcathode lead-out layer 10 (in other words, second region 36 b betweenfirst insulating material 13 of porous part 6 b and cathode lead-outlayer 10) may include second insulating material 7 in an impregnated orfilled state. Further, porous part 6 b of a part of anode section 16 aadjacent to separation section 16 c may include second insulatingmaterial 7 in an impregnated or filled state.

In the case of FIG. 6 , a surface of a recess (neck) may also be coveredwith third insulating material 17 as the same in the case of FIG. 3 .Further, third insulating material 17 may adhere to at least theperiphery of first region 36 a. Third insulating material 17 may coverat least a part of at least one of cathode lead-out layer 10 or solidelectrolyte layer 9. The position of third insulating material 17 can bereferred to in the description of FIG. 3 or 4 . At least a part of asurface of first insulating material 13 may be covered with thirdinsulating material 17.

FIG. 7 is a cross-sectional view schematically illustrating capacitorelement 2 included in a solid electrolytic capacitor according to asixth exemplary embodiment.

In FIG. 7 , first groove 19 is formed by removing porous part 6 b inthird region 36 c. That is, there is no porous part 6 b below firstgroove 19. Meanwhile, the rest of the configuration is the same as inFIG. 6 , and the description of FIGS. 1 and 6 can be referred to. In thecase of FIG. 7 , second insulating material 7 is included in firstgroove 19 as the same in the case of FIG. 6 . Hence, entry of air can besuppressed. Alternatively, at least a part of porous part 6 b in firstregion 36 a may include second insulating material 7 in an impregnated(or filled) state.

FIG. 8 is a cross-sectional view schematically illustrating capacitorelement 2 included in a solid electrolytic capacitor according to aseventh exemplary embodiment. FIG. 9 is a cross-sectional viewschematically illustrating capacitor element 2 included in a solidelectrolytic capacitor according to an eighth exemplary embodiment.These drawings show an example of a case where porous part 6 b exists ina part below first groove 19. These exemplary embodiments are the sameas FIG. 6 except that the structure of first groove 19 is different, andthe description of FIGS. 1 and 6 can be referred to.

In FIG. 8 , in a part of third region 36 c which is close to firstregion 36 a, porous part 6 b exists below first groove 19. In theremaining part of third region 36 c which is close to anode section 16a, porous part 6 b does not exist below first groove 19. A recess whichis close to anode section 16 a is formed at a bottom part of firstgroove 19. Since the recess is filled with second insulating material 7,entry of air can be suppressed. Porous part 6 b below first groove 19may be impregnated (or filled) with second insulating material in a partof third region 36 c which is close to first region 36 a.

In FIG. 9 , porous part 6 b exists below first groove 19 in a part ofthird region 36 c which is close to anode section 16 a, and porous part6 b does not exist below first groove 19 in the remaining part of thirdregion 36 c which is close to first region 36 a. In a bottom part offirst groove 19, a recess which is close to first region 36 a is formedbecause porous part 6 b does not exist. That is, only the position ofporous part 6 b (or recess) below first groove 19 is different from thatin FIG. 8 , and the rest of the configuration is the same as in FIG. 8 .The recess which is close to first region 36 a is filled with secondinsulating material 7, so that entry of air can be suppressed. Porouspart 6 b below first groove 19 in a part of third region 36 c which isclose to anode section 16 a may include second insulating material 7 inan impregnated (or filled) state.

While these drawings show a state in which the recess of the bottom partof first groove 19 is filled with second insulating material 7, thepresent invention is not limited to this case. For example, at least apart of first groove 19 may be covered with second insulating material7. At least a part of first groove 19 may be impregnated or filled withsecond insulating material 7, or the entirety of first groove 19 may befilled with second insulating material 7.

While FIGS. 6 to 9 show the case where first groove 19 is formed at aposition adjacent to first insulating material 13, the present inventionis not particularly limited to this case. First groove 19 may be formedto be apart from first insulating material 13. An example of this caseis shown in FIG. 10 .

FIG. 10 is a cross-sectional view schematically illustrating capacitorelement 2 included in a solid electrolytic capacitor according to aninth exemplary embodiment.

In FIG. 10 , first groove 19 is formed to be apart from first insulatingmaterial 13. First groove 19 is filled with second insulating material7, whereby entry of air is suppressed. While porous part 6 b exists in apart of third region 36 c which is close to first region 36 a, this partmay include second insulating material 7 in an impregnated (or filled)state. Although porous part 6 b does not exist below first groove 19,the present invention is not limited to this case, and porous part 6 bmay be provided below first groove 19. Porous part 6 b below firstgroove 19 may include the second insulating material in an impregnated(or filled) state. The rest of the configuration is the same as in FIG.6 , and the description of FIGS. 1 and 6 can be referred to.

FIG. 11 is a cross-sectional view schematically illustrating capacitorelement 2 included in a solid electrolytic capacitor according to atenth exemplary embodiment. FIG. 12 is a cross-sectional viewschematically illustrating capacitor element 2 included in a solidelectrolytic capacitor according to an eleventh exemplary embodiment.These drawings show an example of a state in which solid electrolytelayer 9 is disposed in at least a part of a region (i.e., second region36 b) in separation section 16 c which is closer to cathode formationsection 16 b than first insulating material 13. By disposing solidelectrolyte layer 9 in at least a part of second region 36 b inseparation section 16 c, entry of air into second region 36 b issuppressed.

In FIG. 11 , thin part 26 is formed in separation section 16 c, andfirst insulating material 13 is disposed on a surface of a part of thinpart 26 which is close to anode section 16 a. In second region 36 b,second groove 29 is formed adjacent to first insulating material 13.Solid electrolyte layer 9 is formed so as to enter into second groove29, so that solid electrolyte layer 9 is disposed in at least a part ofsecond region 36 b.

FIG. 12 is different from FIG. 11 in that, in second region 36 b, secondgroove 29 is formed by removing porous part 6 b, and porous part 6 bdoes not exist below second groove 29. Meanwhile, the rest of theconfiguration is the same as in FIG. 11 , and the description of FIG. 11can be referred to.

Solid electrolyte layer 9 is disposed, at minimum, in at least a part ofsecond region 36 b. For example, solid electrolyte layer 9 may enterinto at least a part of second groove 29. Further, solid electrolytelayer 9 may be disposed so as to cover at least a part of second groove29. From the viewpoint of enhancing the effect of suppressing entry ofair, it is preferable that solid electrolyte layer 9 enters into theentirety of second groove 29 (in other words, second groove 29 is filledwith solid electrolyte layer 9).

In FIGS. 11 and 12 , although not shown, second insulating material 7may also be disposed in at least a part of second groove 29. In thiscase, the leakage current of the solid electrolytic capacitor can besuppressed even more.

FIG. 13 is a cross-sectional view schematically illustrating capacitorelement 2 included in a solid electrolytic capacitor according to atwelfth exemplary embodiment. In FIG. 13 , thin part 26 is formed inseparation section 16 c, and first insulating material 13 is disposed ona surface of thin part 26. In the illustrated example, a groove (thirdgroove 39) is formed by removing porous part 6 b in at least a part ofcathode formation section 16 b. When solid electrolyte layer 9 is formedso as to enter into third groove 39, solid electrolyte layer 9 isdisposed in at least a part of third groove 39.

Solid electrolyte layer 9 may enter into at least a part of third groove39, or may be disposed so as to cover at least a part of third groove39. From the viewpoint of enhancing the effect of suppressing entry ofair, it is preferable that at least the entire surface of porous part 6b around third groove 39 (in other words, entire inner wall of thirdgroove 39) be covered with solid electrolyte layer 9. From the sameviewpoint, it is more preferable that solid electrolyte layer 9 entersinto the entirety of third groove 39 (in other words, third groove 39 isfilled with solid electrolyte layer 9). Further, by filling third groove39 with solid electrolyte layer 9, an effective area of solidelectrolyte layer 9 can be increased.

The shape of third groove 39 is not particularly limited, but may be acolumnar shape (e.g., cylindrical shape or prismatic shape) or a shapein which the diameter decreases from the surface of porous part 6 btoward base material part 6 a (e.g., tapered cross section). In thirdgroove 39, it is preferable that solid electrolyte layer 9 enters into apart having a small diameter as well, and solid electrolyte layer 9 bedisposed therein.

From the viewpoint of easily securing a higher effect for suppressingentry of air into capacitor element 2, it is preferable that thirdgroove 39 be formed at a position closer to separation section 16 c inthe length direction of cathode formation section 16 b. For example,when the length of cathode formation section 16 b is L, it is preferableto form third groove 39 in a region ranging from the boundary ofseparation section 16 c and cathode formation section 16 b to a positionof length 0.3 L (preferably 0.25 L) from the boundary.

Third groove 39 may be formed in the entire region ranging from theboundary of separation section 16 c and cathode formation section 16 bto the position of length 0.3 L (preferably 0.25 L) from this boundary,or may be formed in a part of this region. Third groove 39 may be formedas a single groove extending over the entire region. In cathodeformation section 16 b, single third groove 39 may be formed, or aplurality of third grooves 39 may be formed. The width of third groove39 is, for example, equal to or more than 0.01 μm. The width of thirdgroove 39 may be equal to or more than 0.1 μm, equal to or more than 1μm, or equal to or more than 5 μm. The width of the third groove 39 ispreferably equal to or less than 0.3 L or equal to or less than 0.25 L,and may be equal to or less than 50 μm or equal to or less than 30 μm.The lower limit value and the upper limit value can be arbitrarilycombined. Note that the width of third groove 39 is a length of thirdgroove 39 in a direction along the length direction of cathode formationsection 16 b.

Although porous part 6 b does not exist below third groove 39 in theillustrated example, the present invention is not limited to this case,and porous part 6 b may be provided below third groove 39. From theviewpoint of enhancing the effect of suppressing entry of air, thethickness of porous part 6 b below third groove 39 is preferably small.For example, when the thickness of porous part 6 b is T, the depth ofthird groove 39 is preferably equal to or more than 0.95 T, and may beequal to or more than 0.98 T. The depth of third groove 39 is equal toor less than T, for example. From the viewpoint of enhancing the effectof suppressing entry of air even more, it is preferable that porous part6 b do not exist below third groove 39.

Although FIG. 13 shows an example in which third groove 39 is formed ata position away from separation section 16 c, the present invention isnot limited to this case. Third groove 39 may be formed at a position incathode formation section 16 b adjacent to separation section 16 c.

In the tenth exemplary embodiment, the eleventh exemplary embodiment,and the twelfth exemplary embodiment, separation section 16 c does notneed to include second insulating material 7 unlike in the fifth toninth exemplary embodiments. Meanwhile, the present invention is notlimited to this case, and separation section 16 c may include secondinsulating material 7 as shown in the fifth to ninth exemplaryembodiments. In FIGS. 11 to 13, the states of second region 36 b andthird region 36 c are different from those in FIG. 6 , but the rest ofthe configuration is the same as in FIG. 6 . Hence, the description ofFIGS. 1 and 6 can be referred to. In the twelfth exemplary embodiment,second groove 29 may also be formed, and solid electrolyte layer 9 mayenter into second groove 29 as in the tenth exemplary embodiment or theeleventh exemplary embodiment. Further, second insulating material 7 mayalso be disposed in at least a part of second groove 29. Note that inthe first to ninth exemplary embodiments, second groove 29 and/or thirdgroove 39 may be formed, and solid electrolyte layer 9 may enter intothese grooves as shown in the tenth exemplary embodiment, the eleventhexemplary embodiment, or the twelfth exemplary embodiment. Further,second insulating material 7 may also be disposed in at least a part ofsecond groove 29.

FIG. 14 is a cross-sectional view schematically illustrating capacitorelement 2 included in a solid electrolytic capacitor according to athirteenth exemplary embodiment. In FIG. 14 , thin part 26 is formed inseparation section 16 c, and first insulating material 13 is disposed ona surface of thin part 26. In FIG. 14 , at least in second region 36 b,second groove 29 is formed by removing porous part 6 b. Second groove 29is formed at a position adjacent to first insulating material 13 (orfirst region 36 a). Second groove 29 is filled with second insulatingmaterial 7, whereby entry of air is suppressed. In the illustratedexample, second groove 29 is formed so as to straddle second region 36 band cathode formation section 16 b. Meanwhile, the present invention isnot limited to this case, and there may be a case where second groove 29is formed only in second region 36 b. Further, second groove 29 may beformed in a part of second region 36 b or may be formed in the entiretyof second region 36 b.

Second insulating material 7 does not necessarily have to be included soas to fill the entirety of second groove 29 as shown in FIG. 14 , andmay be disposed in at least a part of second groove 29. Secondinsulating material 7 may be disposed so as to cover at least a part ofsecond groove 29. Alternatively, second groove 29 may be impregnatedwith second insulating material 7. For example, second insulatingmaterial 7 may be included so as to partially fill second groove 29, orsecond insulating material 7 may be disposed on at least a part of aninner surface of second groove 29.

Although porous part 6 b exists in a part of cathode formation section16 b adjacent to second groove 29, this part may include secondinsulating material 7 in an impregnated (or filled) state. Althoughporous part 6 b does not exist below second groove 29 in FIG. 14 , thepresent invention is not limited to this case, and porous part 6 b maybe provided below second groove 29. In the case where porous part 6 b isprovided below second groove 29, porous part 6 b may include secondinsulating material 7 in an impregnated (or filled) state. From theviewpoint of enhancing the effect of suppressing entry of air, it ispreferable that porous part 6 b do not exist below second groove 29.

In the case of FIG. 14 , a surface of a recess (neck) may be coveredwith third insulating material 17 as the same in the case of FIG. 3 .Further, third insulating material 17 may adhere to at least theperiphery of first region 36 a. Third insulating material 17 may coverat least a part of at least one of cathode lead-out layer 10 or solidelectrolyte layer 9. The position of third insulating material 17 can bereferred to in the description of FIG. 3 or 4 .

In FIG. 14 , the states of second region 36 b and third region 36 c aredifferent from those in FIG. 6 , but the rest of the configuration isthe same as in FIG. 6 . Hence, the description of FIGS. 1 and 6 can bereferred to. Further, in FIG. 14 , third region 36 c does not need toinclude second insulating material 7 unlike in the fifth to ninthexemplary embodiments. Meanwhile, the present invention is not limitedto this case, and third region 36 c may include second insulatingmaterial 7 as shown in the fifth to ninth exemplary embodiments. In thethirteenth exemplary embodiment, too, second groove 29 and/or thirdgroove 39 may be formed, and solid electrolyte layer 9 may enter intothese grooves as shown in the tenth exemplary embodiment, the eleventhexemplary embodiment, or the twelfth exemplary embodiment.

Hereinafter, the configuration of the solid electrolytic capacitor willbe described in more detail.

(Capacitor Element 2, 102A to 102C)

Capacitor elements 2, 102A to 102C each include anode foil 6, adielectric layer, and cathode part 8. Cathode part 8 includes solidelectrolyte layer 9 and cathode lead-out layer 10 covering solidelectrolyte layer 9.

The solid electrolytic capacitor has, at minimum, at least one capacitorelement 2, and may have a plurality of capacitor elements (capacitorelements 102A to 102C and the like) as shown in FIG. 5 . The number ofcapacitor elements included in the solid electrolytic capacitor may bedetermined according to the application.

(Anode Foil 6)

Anode foil 6 can include a valve metal, an alloy including a valvemetal, a compound including a valve metal, and the like. These materialscan be used singly or in combination of two or more kinds thereof. Asthe valve metal, for example, aluminum, tantalum, niobium, and titaniumare preferably used. Anode foil 6 including porous part 6 b on a surfaceof base material part 6 a is obtained by roughening a surface of a metalfoil including a valve metal by etching, for example.

(Dielectric Layer)

The dielectric layer is formed by anodizing the valve metal on thesurface of anode foil 6 by anodizing treatment or the like. Thedielectric layer is formed, at minimum, so as to cover at least a partof anode foil 6. The dielectric layer is usually formed on the surfaceof anode foil 6. Since the dielectric layer is formed on the surface ofthe porous part of anode foil 6, the dielectric layer is formed alongthe inner wall surface of pores or pits on the surface of anode foil 6.

The dielectric layer includes an oxide of a valve metal. For example,when tantalum is used as the valve metal, the dielectric layer includesTa₂O₅, and when aluminum is used as the valve metal, the dielectriclayer includes Al₂O₃. Note that the dielectric layer is not limitedthereto, and any dielectric layer may be used as long as the dielectriclayer functions as a dielectric body. When the surface of anode foil 6is porous, the dielectric layer is formed along the surface (includinginner wall surface of hole) of anode foil 6.

(First Insulating Material 13)

As first insulating material 13, an insulating resin or the like isused. From the viewpoint of easily disposing on the surface of porouspart 6 b of separation section 16 c, an insulating tape (resist tape orthe like) is preferably used as first insulating material 13, but firstinsulating material is not limited thereto. First insulating material 13may be a coating film of a coating agent including first insulatingmaterial 13. First insulating material 13 may be a thermoplastic resin(or thermoplastic resin composition), or may be a curable resin (orcurable resin composition) or a cured product (including semi-curedproduct) thereof. The curable resin (or curable resin composition) maybe a thermosetting resin or a photocurable resin.

Examples of the insulating resin include a curable resin (epoxy resin,polyimide, and the like), a photoresist, and a thermoplastic resin(e.g., polyolefin, polyester, polyamide, thermoplastic polyimide, andthe like). The curable resin may be either a thermosetting resin or aphotocurable resin. The photocurable resin may be cured by visible lightor ultraviolet light. As the insulating resin, a composition of acurable resin may be used. The insulating resin may be used alone, ormay be used in combination of two or more kinds thereof.

(Second Insulating Material 7)

As second insulating material 7, an insulating resin or the like isused. From the viewpoint of easily securing high permeability orpenetrability into porous part 6 b, first groove 19, or second groove29, second insulating material 7 is preferably a cured product(including semi-cured product) of a curable resin or a compositionthereof. The curable resin may be a thermosetting resin or aphotocurable resin. Examples of the photocurable resin or thecomposition thereof include those cured by ultraviolet rays, visiblelight, or the like. From the viewpoint of easily impregnating or fillingfirst groove 19 or second groove 29, it is preferable to use aphotocurable (in particular, ultraviolet curability) resin or acomposition thereof. Examples of the curable resin include thosedescribed later. The curable resin composition may include, for example,at least one selected from the group consisting of a curing agent, acuring accelerator, a catalyst, and an additive.

(Third Insulating Material 17)

As third insulating material 17, an insulating resin or the like isused. Third insulating material 17 may be a thermoplastic resin, or maybe a cured product of a curable resin or a composition thereof. Thirdinsulating material 17 may be the same as or different from secondinsulating material 7. Examples of the curable resin include thoseexemplified later for second insulating material 7.

Examples of the thermoplastic resin include at least one selected fromthe group consisting of vinyl resin (e.g., vinyl chloride, vinylacetate, and aromatic vinyl resin), polyolefin (e.g., polyethylene andpolypropylene), acrylic resin, polyamide, polycarbonate, thermoplasticpolyimide, and polyamideimide. Examples of the aromatic vinyl resininclude polystyrene and an acrylonitrile-butadiene-styrene copolymer(ABS resin).

(Fourth Insulating Material 117)

Fourth insulating material 117 can be selected from those exemplified asthird insulating material 17, for example. From the viewpoint of easilyforming a thin film, fourth insulating material 117 is preferably acured product of a curable resin or a composition thereof. The curableresin may be thermosetting or photocurable. Fourth insulating material117 may be the same as or different from second insulating material 7.Fourth insulating material 117 may be the same as or different fromthird insulating material 17.

(Cathode Part 8)

(Solid Electrolyte Layer 9)

Solid electrolyte layer 9 constituting cathode part 8 includes aconductive polymer, but may also include a dopant, an additive, or thelike as necessary. Examples of the conductive polymer includepolypyrrole, polythiophene, polyaniline, and derivatives thereof. Solidelectrolyte layer 9 can be formed by chemical polymerization and/orelectrolytic polymerization of a raw material monomer, for example.Alternatively, solid electrolyte layer 9 can be formed by bringing thedielectric layer into contact with a solution in which the conductivepolymer is dissolved or a dispersion liquid in which the conductivepolymer is dispersed. Solid electrolyte layer 9 is formed, at minimum,so as to cover at least a part of the dielectric layer. In the case ofelectrolytic polymerization, a conductive precoat layer may be formedprior to electrolytic polymerization. Solid electrolyte layer 9 may beformed directly on the dielectric layer or may be formed with a precoatlayer interposed therebetween.

(Cathode Lead-Out Layer 10)

Cathode lead-out layer 10 constituting cathode part 8 includes carbonlayer 11 and metal paste layer 12. Carbon layer 11 has, at minimum,conductivity, and can be made of, for example, a conductive carbonmaterial such as graphite. Metal paste layer 12 may be a silver pastelayer. For the silver paste layer, a composition including a silverpowder and a binder resin (epoxy resin or the like) can be used, forexample. Note that cathode lead-out layer 10 is not limited to thisconfiguration, and may be configured in any way as long as it has acurrent collecting function. Cathode lead-out layer 10 is formed so asto cover at least a part of solid electrolyte layer 9.

(Exterior Body 3)

Exterior body 3 covers a part of capacitor element 2 and lead terminals4, 5. From the viewpoint of suppressing entry of air into exterior body3, it is preferable that capacitor element 2 and a part of each of leadterminals 4, 5 are sealed with exterior body 3. Although FIGS. 1 and 2show the case where exterior body 3 is a resin exterior body, thepresent invention is not limited to this case, and exterior body 3 maybe a case or the like capable of housing capacitor element 2. The resinexterior body is formed by sealing capacitor element 2 and a part ofeach of lead terminals 4 and 5 with a resin material. Examples of thecase include a combination of a container that houses capacitor element2 and a sealing body that covers an opening of the container. Thecontainer and the sealing body are formed of a metal material or a resinmaterial, for example.

The resin exterior body preferably includes a cured product of a curableresin composition, and may include a thermoplastic resin or acomposition including the thermoplastic resin. Examples of the resinmaterial forming the case include a thermoplastic resin or a compositionincluding the thermoplastic resin. Examples of the metal materialforming the case include metals such as aluminum, copper, and iron, oralloys thereof (also including stainless steel, brass, and the like).

(Lead Terminals 4, 5)

One end of each of lead terminals 4, 5 is electrically connected tocapacitor element 2, and the other end of lead terminals 4, 5 is drawnout of exterior body 3. In solid electrolytic capacitor 1, the one endof each of lead terminals 4, 5 is covered with exterior body 3 togetherwith capacitor element 2. A lead terminal usually used in a solidelectrolytic capacitor can be used as lead terminals 4, 5, withoutparticular limitation. And a so-called lead frame, for example, may beused as lead terminals 4, 5. Examples of the material of lead terminals4, 5 include a metal such as copper or an alloy thereof.

[Method for Manufacturing Solid Electrolytic Capacitor]

The solid electrolytic capacitor can be manufactured, for example, by amanufacturing method including: a step (first step) of preparing acapacitor element, a step (second step) of electrically connecting alead terminal to the capacitor element, and a step (third step) ofcovering a part of the capacitor element and the lead terminal with anexterior body.

Hereinafter, each step will be described in more detail.

(First Step)

In the first step, capacitor elements 2, 102A to 102C are produced. Thefirst step can include a step of preparing anode foil 6, a step offorming a dielectric layer, a step of forming separation section 16 c, astep of disposing or impregnating with first insulating material 13, astep of forming solid electrolyte layer 9, and a step of forming cathodelead-out layer 10. The first step can include a step of disposing orimpregnating at least a part of separation section 16 c with the secondinsulating material. The first step may include a step of covering atleast a part of first insulating material 13, solid electrolyte layer 9,cathode lead-out layer 10, or the like with third insulating material17.

(Step of Preparing Anode Foil 6)

Anode foil 6 can be prepared, for example, by roughening a surface of ametal foil including a valve metal. Porous part 6 b is formed on asurface of base material part 6 a by roughening. The roughening may beperformed in any way as long as irregularities can be formed on thesurface of the base material part. The roughening may be performed byetching (e.g., electrolytic etching) the surface of the metal foil, forexample.

(Step of Forming Dielectric Layer)

In this step, a dielectric layer is formed on anode foil 6. Thedielectric layer is formed by anodizing anode foil 6. The anodizationcan be performed by a known method such as an anodizing treatment. Theanodizing treatment can be performed, for example, by immersing anodefoil 6 in an anodizing solution and applying a voltage between anodefoil 6 as an anode and a cathode immersed in the anodizing solution. Asthe anodizing solution, for example, a phosphoric acid aqueous solutionor the like is preferably used.

(Step of Forming Separation Section 16 c)

Anode foil 6 on which the dielectric layer is formed is defined intoanode section 16 a, cathode formation section 16 b, and separationsection 16 c located between anode section 16 a and cathode formationsection 16 b. Then, at least a part of porous part 6 b is compressedand/or removed in at least a part of separation section 16 c. Forexample, in at least a part of separation section 16 c, porous part 6 bmay be compressed or partially removed to form a groove (or thin part26). If necessary, compression and removal may be combined. Thecompression can be performed by press working or the like. The removalof porous part 6 b can be performed by cutting, laser processing, or thelike.

In a case where first groove 19 is formed in third region 36 c, firstgroove 19 may be formed in this step. First groove 19 can be formed bycompressing or removing porous part 6 b in third region 36 c, as thesame in the case of the groove described above. First groove 19 may beformed continuously with first region 36 a or may be formed to be apartfrom first region 36 a.

In a case where second groove 29 is formed in second region 36 b, secondgroove 29 may be formed in this step. Second groove 29 can be formed bycompressing or removing porous part 6 b in second region 36 b, as thesame in the case of the groove described above. Second groove 29 may beformed continuously with first region 36 a or may be formed apart fromfirst region 36 a.

In a case where third groove 39 is formed in cathode formation section16 b, third groove 39 may be formed in this step. Third groove 39 can beformed by compressing or removing porous part 6 b in cathode formationsection 16 b, as the same in the case of the groove described above.Third groove 39 may be formed continuously with second region 36 b ormay be formed apart from second region 36 b.

Note that first groove 19 and second groove 29 do not necessarily haveto be formed in this step, and may be formed after this step and beforethe step of forming solid electrolyte layer 9. Third groove 39 does notnecessarily have to be formed in this step, and may be formed after thestep of forming the dielectric layer and before the step of formingsolid electrolyte layer 9.

(Step of Disposing or Impregnating with First Insulating Material 13)

First insulating material 13 is disposed in or used to impregnate atleast a part of separation section 16 c. First insulating material 13 ispreferably disposed on a surface of thin part 26. For example, firstinsulating material 13 may be disposed by attaching an insulating tape(such as resist tape) to a surface of separation section 16 c, or may bedisposed on a surface of porous part 6 b by coating with a coating agentincluding first insulating material 13. By disposing first insulatingmaterial 13 prior to the step of forming solid electrolyte layer 9, itis possible to suppress the creeping of the conductive polymer towardanode section 16 a when solid electrolyte layer 9 is formed. Examples ofthe first insulating material include an insulating resin.

In the solid electrolytic capacitor according to a second aspect of thepresent disclosure, first insulating material 13 may be formed byimpregnating at least a part of separation section 16 c with a coatingagent including first insulating material 13. Alternatively, firstinsulating material 13 may be disposed by attaching an insulating tapeto the surface of separation section 16 c, and at least a part ofseparation section 16 c may be impregnated with a coating agentincluding first insulating material 13. Any of the impregnation with thecoating agent and the placement of the insulating tape can be performedfirst.

(Step of Forming Solid Electrolyte Layer 9)

In this step, solid electrolyte layer 9 is formed on the dielectriclayer. Solid electrolyte layer 9 is formed, at minimum, so as to coverat least a part of the dielectric layer. Solid electrolyte layer 9includes a conductive polymer, but may also include a dopant, anadditive, or the like as necessary.

As the conductive polymer, for example, polypyrrole, polythiophene (poly(3,4-ethylenedioxythiophene) (PEDOT), and the like), polyaniline,derivatives thereof, and the like are used. As the dopant, for example,paratoluenesulfonic acid, naphthalenesulfonic acid, polystyrenesulfonicacid (PSS), or the like is used.

Solid electrolyte layer 9 can be formed by chemical polymerizationand/or electrolytic polymerization of a raw material monomer, forexample. Alternatively, the solid electrolyte layer 9 can be formed bybringing the dielectric layer into contact with a solution in which theconductive polymer is dissolved or a solution or dispersion liquid inwhich the conductive polymer is dissolved or dispersed in a liquidmedium (solvent or the like). Examples of the liquid medium includewater, an organic solvent, and a mixture thereof. In particular, at theouter surface (the surface opposite to dielectric layer) of the solidelectrolyte layer, the electrolytic polymerization easily proceeds andthus solid electrolyte layer 9 tends to be densely formed. On the otherhand, at the inside surface of the solid electrolyte layer, theelectrolytic polymerization hardly proceeds, and thus voids in the solidelectrolyte layer tend to be generated. Hence, air easily enterscapacitor element 2 through the voids. From this, the effect of fillingporous part 6 b with the second insulating material is remarkablyexhibited particularly when solid electrolyte layer 9 is formed byelectrolytic polymerization. Note that in the case of electrolyticpolymerization, a precoat layer may be formed on the dielectric layerprior to electrolytic polymerization. The precoat layer is made of aconductive material (conductive polymer, inorganic conductive material,and the like), for example. The conductive material constituting theprecoat layer is not particularly limited, and a known material can beused, for example.

When solid electrolyte layer 9 is disposed in at least a part (e.g., atleast a part of second groove 29) of second region 36 b in separationsection 16 c, solid electrolyte layer 9 can be formed in second region36 b by, for example, performing chemical polymerization or electrolyticpolymerization while second region 36 b is in contact with apolymerization liquid, or bringing a solution or dispersion liquidcontaining a conductive polymer into contact with second region 36 b.

When solid electrolyte layer 9 is disposed in at least a part of thirdgroove 39, solid electrolyte layer 9 can be formed in third groove 39by, for example, performing chemical polymerization or electrolyticpolymerization while third groove 39 is in contact with a polymerizationliquid, or bringing a solution or dispersion liquid containing aconductive polymer into contact with third groove 39.

(Step of Forming Cathode Lead-Out Layer 10)

In this step, carbon layer 11 and metal paste layer 12 are sequentiallylaminated on solid electrolyte layer 9 to form cathode lead-out layer10.

Note that as shown in FIG. 5 , when a plurality of capacitor elementsare laminated, a laminated body of the capacitor elements may beprepared in the first step by producing each capacitor element asdescribed above and then laminating the plurality of capacitor elements.

(Step of Disposing or Impregnating with Second Insulating Material)

The second insulating material may be disposed in or used to impregnateat least a part of separation section 16 c. When second groove 29 isprovided so as to straddle separation section 16 c and cathode formationsection 16 b, second groove 29 may be impregnated with second insulatingmaterial 7. In this case, second insulating material 7 is included notonly in a part of separation section 16 c but also in a part of cathodeformation section 16 b.

The method for manufacturing a solid electrolytic capacitor according toa first aspect of the present disclosure can include a step ofimpregnating porous part 6 b of at least first region 36 a with thesecond insulating material. Porous part 6 b of at least first region 36a may be impregnated (or filled) with the second insulating material.Porous part 6 b of at least first region 36 a is filled with the secondinsulating material by impregnating the periphery of first insulatingmaterial 13 with the second insulating material. At this time, porouspart 6 b of at least one of second region 36 b at a side close tocathode formation section 16 b or third region 36 c at a side close toanode section 16 a may be impregnated (or filled) with the secondinsulating material. Further, as in the case of FIG. 4 , metal pastelayer 12 may be impregnated with the second insulating material.

When manufacturing the solid electrolytic capacitor according to thesecond aspect of the present disclosure, second insulating material 7may be disposed in or used to impregnate at least a part of a regionlocated closer to anode section 16 a than first insulating material 13(i.e., third region 36 c) in separation section 16 c. For example, firstgroove 19 may be formed in at least a part of third region 36 c, andsecond insulating material 7 may be disposed in at least a part of firstgroove 19. At this time, second insulating material 7 may be disposed soas to cover at least a part of first groove 19. Alternatively, porouspart 6 b in at least a part of third region 36 c may be impregnated withsecond insulating material 7. These configurations may be combined.

Second insulating material 7 may be disposed in or used to impregnate atleast third region 36 c. First groove 19 is preferably impregnated orfilled with second insulating material 7. First region 36 a and/orsecond region 36 b at a side close to cathode formation section 16 b maybe impregnated or filled with second insulating material 7. For example,first region 36 a may be filled with second insulating material 7 byimpregnating the periphery of first insulating material 13 with secondinsulating material 7. Porous part 6 b located closer to anode section16 a than third region 36 c may be impregnated or filled with secondinsulating material 7.

When manufacturing the solid electrolytic capacitor according to a fifthaspect of the present disclosure, second insulating material 7 isdisposed in at least a part of second groove 29 formed to be adjacent tofirst insulating material 13 (or first region 36 a) at a side close tocathode formation section 16 b in separation section 16 c. At least apart of second groove 29 may be covered with second insulating material7. Second groove 29 may be impregnated or filled with second insulatingmaterial 7. By impregnating second groove 29 with the second insulatingmaterial, at least a part of cathode formation section 16 b locatedadjacent to second groove 29 may be impregnated or filled with thesecond insulating material.

The step of impregnating with second insulating material 7 may beperformed after the step of forming cathode lead-out layer 10. Metalpaste layer 12 may be impregnated with second insulating material 7.

Note that when the step of impregnating with second insulating material7 is performed after the step of forming cathode lead-out layer 10,second insulating material 7 may be disposed so as to cover at least apart of solid electrolyte layer 9 or cathode lead-out layer 10. Secondinsulating material 7 may be disposed so as to cover at least a part ofa surface of a recess (neck) between cathode part 8 and separationsection 16 c (or first insulating material 13). Second insulatingmaterial 7 disposed so as to cover at least a part of solid electrolytelayer 9, cathode lead-out layer 10, the neck, and the like correspondsto third insulating material 17 in FIG. 3 or 4 . Third insulatingmaterial 17 disposed in this manner is the same material as secondinsulating material 7.

The second insulating material can be supplied to the surfaces of firstregion 36 a, second region 36 b, third region 36 c, porous part 6 b, andcapacitor element 2 by a known coating method. The second insulatingmaterial is supplied by using, for example, a coating method or adispensing method using various coaters or dispenses, immersion,transfer (roller transfer or the like), or the like.

From the viewpoint of easily impregnating first groove 19, second groove29, or porous part 6 b with the second insulating material, it ispreferable to use a curable resin (or a composition thereof) as thesecond insulating material. The curable resin may be a photocurableresin or a thermosetting resin. Examples of the curable resin include,but are not limited to, epoxy resin, phenol resin, unsaturated polyesterresin, thermosetting polyurethane resin, and thermosetting polyimide.The curable resins may be used alone, or may be used in combination oftwo or more kinds thereof. The curable resin may be a one-componentcurable resin or a two-component curable resin. The curable resincomposition may include, for example, at least one selected from thegroup consisting of a curing agent, a curing accelerator, a catalyst,and an additive.

From the viewpoint of easily impregnating first groove 19, second groove29, or porous part 6 b with the second insulating material, the curableresin (or composition) supplied to porous part 6 b preferably has a lowviscosity. The viscosity of the curable resin (or composition) at 25° C.is equal to or less than 300 mPa·s, and more preferably equal to or lessthan 100 mPa·s, for example.

Note that the viscosity of the curable resin (or composition) can bemeasured under the condition of a rotation speed of 60 rpm using acone-plate viscometer.

Since it is preferable that the thermosetting resin (or composition)have a low viscosity, the thermosetting resin (or composition) mayinclude a solvent. From the viewpoint of easily and efficiently fillingmany voids included in first groove 19, second groove 29, or porous part6 b with the second insulating material, a solvent-free curable resin(or composition) is preferably used.

The curable resin includes, for example, a polyfunctional compoundhaving two or more polymerizable functional groups involved in thecuring reaction and/or a monofunctional compound having onepolymerizable functional group. From the viewpoint of lowering theviscosity of the curable resin (or composition), the curable resin (orcomposition) preferably includes at least a monofunctional compound. Thecurable resin may include a monofunctional compound and a polyfunctionalcompound. In the case of epoxy resin, for example, a monofunctionalglycidyl compound (glycidyl ether of monohydroxy compound, glycidylamine, and the like) and a polyfunctional glycidyl compound(polyglycidyl ether of polyhydroxy compound, polyglycidyl amine, and thelike) may be combined. The polyfunctional compound may have, forexample, 2 to 4 or 2 or 3 polymerizable functional groups.

The proportion of the monofunctional compound in the curable resin is,for example, preferably equal to or more than 50 mass %, and may beequal to or more than 70 mass %. When the proportion of themonofunctional compound is in such a range, the viscosity of the curableresin (or composition) can be lowered even if the content of the solventis low (in particular, even when solvent-free curable resin (orcomposition) is used). The proportion of the monofunctional compound inthe curable resin is, for example, equal to or less than 90 mass %, andmay be equal to or less than 85 mass %. The lower limit value and theupper limit value can be arbitrarily combined.

The curable resin composition preferably includes a curing agent. Thecuring agent is selected according to the type of the curable resin. Forexample, in the case of epoxy resin, examples of the curing agentinclude at least one selected from the group consisting of an aminecompound, an acid anhydride, a phenol compound, a polymerized catalyst,and a latent curing agent.

The curing agent may be combined with a curing accelerator. The curingaccelerator is selected according to the type of the curable resin.Examples of the curing accelerator include tertiary amines or saltsthereof, imidazole, phosphine, phosphonium salts, and sulfonium salts.

The thermosetting resin (or composition) that has been supplied to thesurface of capacitor element 2 or the second insulating material thathas filled first groove 19, second groove 29, or porous part 6 b may becured in at least one of this step or the subsequent step, as necessary.

(Step of Covering Solid Electrolyte Layer 9, Cathode Lead-Out Layer 10or Other Parts with Third Insulating Material)

The first step may include a step of covering, with third insulatingmaterial 17, at least a part of at least one selected from the groupconsisting of the first insulating material, solid electrolyte layer 9,cathode lead-out layer 10, and the neck. Third insulating material 17may be the same as or different from the second insulating material.This step may be performed after the step of forming cathode lead-outlayer 10.

By coating, with a coating agent including third insulating material 17,at least a part of a surface of at least one selected from the groupconsisting of the first insulating material, solid electrolyte layer 9,cathode lead-out layer 10, and the neck, the surface can be covered withthe third insulating material. Third insulating material 17 is suppliedto the surface using, for example, a coating method or a dispensingmethod using various coaters or dispenses, immersion, transfer (rollertransfer, or the like), or the like.

The curable resin (or curable resin composition) disposed on the surfaceby coating or the like may be cured in at least one of this step or thesubsequent step, as necessary.

(Step of Covering a Part of Laminated Body with Fourth InsulatingMaterial 117)

As shown in FIG. 5 , when a plurality of capacitor elements arelaminated, the first step may further include a step of covering atleast a part of a surface of the laminated body with fourth insulatingmaterial 117. In this case, fourth insulating material 117 may be thesame as or different from second insulating material 7. Further, fourthinsulating material 117 may be the same as or different from thirdinsulating material 17.

For example, as in the case of third insulating material 17, a coatingagent including fourth insulating material 117 is coated on at least apart of the surface of the laminated body, whereby a film of fourthinsulating material 117 is formed on the surface of the laminated body.

The curable resin (or curable resin composition) disposed so as to coverat least a part of the surface of the laminated body by coating or thelike may be cured in at least one of this step or the subsequent step,as necessary.

(Second Step)

In the second step, each of anode lead terminal 4 and cathode leadterminal 5 is electrically connected to capacitor elements 2, 102A to102C. The lead terminals may be connected after the capacitor element isproduced in the first step. While cathode lead terminal 5 is connectedto the capacitor element after the capacitor element is produced, anodelead terminal 4 may be connected to anode foil 6 at an appropriate stagein the step of producing the capacitor element.

When a laminated body of a plurality of capacitor elements is used,anode lead terminal 4 can be connected to anode foil 6 in the samemanner as described above. Cathode lead terminal 5 may be connected to acapacitor element in the same manner as described above, or one end ofcathode lead terminal 5 may be connected to a laminated body of aplurality of capacitor elements in which cathode parts 8 areelectrically connected to each other.

(Third Step)

In the third step, capacitor elements 2, 102A to 102C and a part of eachof lead terminals 4, 5 are covered with exterior body 3, so that thecapacitor elements are sealed with exterior body 3. The sealing can beperformed according to the type of exterior body 3.

For example, when a case-shaped exterior body including a container anda sealing body is used, a capacitor element is housed in the container,and an opening of the container can be covered and sealed with a sealingbody in a state where the other end of a lead terminal connected to thecapacitor element is drawn out from a through hole formed in the sealingbody.

When the resin exterior body is adopted, capacitor element 2 and leadterminals 4, 5 are electrically connected to each other, and thencapacitor element 2 and a part of each of lead terminals 4, 5 arecovered with a resin forming the resin exterior body to be sealed. Theresin exterior body can be formed by using a molding technique such asinjection molding, insert molding, or compression molding.

EXAMPLES

Hereinafter, the present disclosure will be specifically described basedon examples and comparative examples, but the present disclosure is notlimited to the following examples.

Example 1

Solid electrolytic capacitor A1 including a laminated body in whichseven capacitor elements 2 shown in FIG. 2 were laminated was producedin the following manner.

(1) Production of Capacitor Element 2

An aluminum foil (thickness of 100 μm) was prepared as a base material,and a surface of the aluminum foil was subjected to an etching treatmentto obtain anode foil 6 including porous part 6 b. Anode foil 6 wasimmersed in a phosphoric acid solution (liquid temperature of 70° C.)having a concentration of 0.3 mass %, and a direct-current voltage of 70V was applied for 20 minutes to form a dielectric layer includingaluminum oxide (Al₂O₃) on a surface of anode foil 6. Anode foil 6 wasdefined into anode section 16 a, cathode formation section 16 b, andseparation section 16 c therebetween, and a part of separation section16 c was compressed by press working to form thin part 26. Insulatingresist tape (first insulating material) 13 was attached to thin part 26.

Anode foil 6 on which the dielectric layer was formed was immersed in aliquid composition including a conductive material to form a precoatlayer.

A polymerization liquid containing pyrrole (monomer of conductivepolymer), naphthalenesulfonic acid (dopant), and water was prepared.Anode foil 6 on which the dielectric layer and the precoat layer wereformed was immersed in the obtained polymerization liquid, andelectropolymerization was performed at an applied voltage of 3 V to formsolid electrolyte layer 9.

A dispersion liquid in which graphite particles were dispersed in waterwas applied to solid electrolyte layer 9, and then solid electrolytelayer 9 was dried to form carbon layer 11 on a surface of solidelectrolyte layer 9. Then, a silver paste containing silver particlesand a binder resin (epoxy resin) was applied onto a surface of carbonlayer 11, and then the binder resin was cured by heating to form metalpaste layer (silver paste layer) 12. Cathode lead-out layer 10 composedof carbon layer 11 and metal paste layer 12 was thus formed. Cathodepart 8 formed of solid electrolyte layer 9 and cathode lead-out layer 10was thus formed.

Then, a two-component curable epoxy resin (solvent-free type, viscosity(25° C.): 100 mPa·s) was supplied around the resist tape by rollertransfer to impregnate porous part 6 b of anode foil 6 with the epoxyresin. As a result, porous part 6 b (porous part 6 b of second region 36b and third region 36 c) around the resist tape and the region of porouspart 6 b of first region 36 a covered with the resist tape wereimpregnated with the epoxy resin. Then, the impregnated epoxy resin wascured.

In this way, capacitor element 2 was formed. Note that as the epoxyresin, liquid A composed of 4-tert butyl phenyl glycidyl ether:bisphenol F type epoxy resin (mass ratio)=75:25 and liquid B containingan acid anhydride curing agent and an imidazole curing accelerator weremixed and used.

(2) Assembly of Solid Electrolytic Capacitor 1

Anode lead terminal 4, cathode lead terminal 5, and adhesive layer 14were also disposed on capacitor element 2 obtained in (1). Exterior body3 was formed by sealing, with a resin, a laminated body in which sevensuch capacitor elements 2 were laminated, thereby completing solidelectrolytic capacitor A1.

Example 2

Solid electrolytic capacitor A2 including a laminated body in whichseven capacitor elements 2 shown in FIG. 4 were laminated was produced.

After cathode lead-out layer 10 was formed, capacitor element 2 wasimmersed in the same epoxy resin as the epoxy resin used in Example 1 upto the periphery of the resist tape (first insulating material 13) at aside close to anode section 16 a, was taken out, and then the epoxyresin was cured. Other than this, solid electrolytic capacitor 1 wascompleted in the same manner as in Example 1. In Example 2, porous part6 b (porous part 6 b of second region 36 b and third region 36 c) aroundthe resist tape and the region of porous part 6 b of first region 36 acovered with the resist tape are impregnated with the epoxy resin.Further, a surface of the solid electrolyte layer or the firstinsulating material between the first insulating material and the end ofcathode lead-out layer 10 at a side close to the anode section iscovered with the epoxy resin. Metal paste layer 12 is also impregnatedwith the epoxy resin.

Comparative Example 1

A solid electrolytic capacitor R1 was produced in the same manner as inExample 1 except that the epoxy resin was not supplied to the peripheryof the resist tape or a surface of the capacitor element.

[Evaluation]

For the solid electrolytic capacitors of Examples 1 and 2 andComparative Example 1 produced above, the change rates in capacitance,ESR, and dielectric loss tangent tan δ were evaluated in the followingprocedure.

Under an environment of 20° C., an initial capacitance value C0 (μF), aninitial ESR value X0 (mΩ) at a frequency of 100 kHz and an initialdielectric loss tangent tan δ0 at 120 kHz with respect to the solidelectrolytic capacitor were measured using an LCR meter for 4-terminalmeasurement. Next, a rated voltage was applied to the solid electrolyticcapacitor at a temperature of 145° C. for 1000 hours (heat resistancetest). Thereafter, a capacitance value C1 (μF), an ESR value X1 (mΩ),and a dielectric loss tangent tan δ1 were measured in the same manner asdescribed above. Then, a value obtained by subtracting the initialcapacitance value C0 from the capacitance value C1 was divided by theinitial capacitance value Cand multiplied by 100 to obtain a change rate(%) of the capacitance. Further, a value obtained by subtracting theinitial ESR value X0 from the ESR value X1 was divided by the ESR valueX0 and multiplied by 100 to obtain a change rate (%) of the ESR.Further, a value obtained by subtracting the initial dielectric losstangent tan δ0 from the dielectric loss tangent tan δ1 was divided bythe dielectric loss tangent tan δ0 and multiplied by 100 to obtain achange rate (%) of the dielectric loss tangent tan δ.

The results are shown in Table 1.

TABLE 1 Change rate of Change rate of Change rate of capacitance (%) ESR(%) tanδ (%) A1 −12.6 55.4 12.6 A2 −5.6 36.3 48.6 R1 −38.2 4484.3 1505.6

In Examples 1 and 2, the change rate in each of capacitance, ESR, andtan δ was smaller than that in Comparative Example 1. In Examples 1 and2, it is considered that by impregnating porous part 6 b of first region36 a and other parts with the second insulating material (epoxy resin),the contact of air with solid electrolyte layer 9 was suppressed, andthe deterioration of the conductive polymer was suppressed, so that heatresistance of the solid electrolytic capacitor was improved.

Example 3

A solid electrolytic capacitor including a laminated body in which sevencapacitor elements 2 shown in FIG. 6 were laminated was produced in thefollowing manner.

In step (1) of Example 1, insulating resist tape (first insulatingmaterial) 13 was attached to a part of thin part 26 at a side close tocathode formation section 16 b. Thus, first groove 19 is formed by thinpart 26 and the resist tape in a region located closer to anode section16 a than the resist tape.

Then, a two-component curable epoxy resin (solvent-free type, viscosity(25° C.): 100 mPa·s) was supplied to first groove 19 by roller transferto impregnate porous part 6 b of anode foil 6 with the epoxy resin. As aresult, first groove 19 was impregnated with the epoxy resin, and porouspart 6 b around first groove 19 (porous part 6 b of third region 36 c,part of porous part 6 b of first region 36 a, and porous part 6 b at aside close to anode section 16 a adjacent to third region 36 c) wasimpregnated with the epoxy resin. Then, the impregnated epoxy resin wascured.

Other than these, a solid electrolytic capacitor (electrolytic capacitorA3) was produced in the same manner as in Example 1.

Comparative Example 2

A solid electrolytic capacitor (solid electrolytic capacitor R2) wasproduced in the same manner as in Example 3 except that the epoxy resinwas not supplied to the periphery of the resist tape or a surface of thecapacitor element.

Example 4

A solid electrolytic capacitor including a laminated body in which sevencapacitor elements 2 shown in FIG. 12 were laminated was produced in thefollowing manner.

In step (1) of Example 3, a part (second region 36 b) of cathodeformation section 16 b in thin part 26 was laser-etched to form secondgroove 29. A resist tape was attached to the entire surface of thin part26. Further, no epoxy resin was supplied around the resist tape or tothe surface of the capacitor element. Other than these, a solidelectrolytic capacitor (solid electrolytic capacitor A4) was produced inthe same manner as in Example 3.

Examples 3 and 4 and Comparative Example 2 were evaluated in the samemanner as in Example 1. The results are shown in Table 2.

TABLE 2 Change rate of Change rate of Change rate of capacitance (%) ESR(%) tanδ (%) A3 −1.2 680 16 A4 −1.3 600 19 R2 −6.6 800 320

In Examples 3 and 4, the change rate in each of capacitance, ESR, andtan δ was smaller than that in Comparative Example 2. In Example 3, itis considered that by impregnating third region 36 c with the secondinsulating material (epoxy resin), the contact of air with solidelectrolyte layer 9 was suppressed, and the deterioration of theconductive polymer was suppressed, so that heat resistance of the solidelectrolytic capacitor was improved. Further, in Example 4, it isconsidered that since the conductive polymer was disposed in secondgroove 29, air hardly entered second region 36 b, and deterioration ofthe conductive polymer in solid electrolyte layer 9 at a side close tocathode formation section 16 b was suppressed.

Although the present invention has been described in terms of presentlypreferred exemplary embodiments, such disclosure should not be construedin a limiting manner. Various modifications and alterations willundoubtedly become apparent to those skilled in the art to which thepresent invention belongs upon reading the above disclosure.Accordingly, the appended claims are to be construed to cover allmodifications and alterations without departing from the true spirit andscope of the present invention.

In the solid electrolytic capacitor according to the present disclosure,deterioration of the conductive polymer included in the solidelectrolyte layer is suppressed even when the solid electrolyticcapacitor is exposed to a high-temperature atmosphere, and a decrease incapacitance can be suppressed. It is also possible to suppress anincrease in ESR and an increase in tan δ. Hence, the electrolyticcapacitor can be used in various applications such as applicationsrequiring low ESR and high capacitance of the solid electrolyticcapacitor, and applications exposed to heat. These applications aremerely examples, and the present invention is not limited thereto.

The invention claimed is:
 1. A solid electrolytic capacitor comprising: a capacitor element including: an anode foil including a base material part and a porous part disposed on a surface of the base material part; a dielectric layer disposed on at least a part of a surface of the anode foil; a solid electrolyte layer covering at least a part of the dielectric layer; and a cathode lead-out layer covering at least a part of the solid electrolyte layer, wherein: the anode foil includes an anode section, a cathode formation section, and a separation section located between the anode section and the cathode formation section, the cathode formation section being covered with the solid electrolyte layer, the anode section being not covered with the solid electrolyte layer and other than the separation section, a first insulating material is disposed on a surface of the porous part in the separation section, the porous part of the separation section has a first region, a second region, and a third region, the first region being located between the first insulating material and the base material part, the second region being located closer to the cathode formation section than the first insulating material, the third region being located closer to the anode section than the first insulating material, voids of the porous part in at least a part of the first region are filled with a second insulating material, and voids of the porous part in at least a part of the third region are filled with the second insulating material.
 2. The solid electrolytic capacitor according to claim 1, wherein voids of the porous part in at least a part of the second region are filled with the second insulating material.
 3. The solid electrolytic capacitor according to claim 1, wherein the second insulating material is included in the porous part in the cathode formation section.
 4. The solid electrolytic capacitor according to claim 1, wherein at least a part of the cathode lead-out layer includes the second insulating material.
 5. The solid electrolytic capacitor according to claim 1, wherein a third insulating material covers at least a part of the solid electrolyte layer between the first insulating material and an end of the cathode lead-out layer, the end of the cathode lead-out layer being at a side close to the anode section.
 6. The solid electrolytic capacitor according to claim 5, wherein the third insulating material covers at least a part of the cathode lead-out layer.
 7. The solid electrolytic capacitor according to claim 1 comprising a laminated body in which a plurality of the capacitor elements are laminated, each of the plurality of the capacitor elements being the capacitor element, wherein an insulating material covers at least a part of a surface of the laminated body.
 8. A method for manufacturing a solid electrolytic capacitor, the method comprising: (i) forming a dielectric layer on at least a part of a surface of an anode foil, the anode foil including a base material part and a porous part disposed on a surface of the base material part; (ii) conducting at least one of compression or removal of, after defining an anode section, a cathode formation section, and a separation section between the anode section and the cathode formation section in the anode foil on which the dielectric layer is formed, at least a part of the porous part in the separation section; (iii) disposing a first insulating material in at least a part of the separation section or impregnating the at least a part of the separation section with the first insulating material; (iv) covering at least a part of the dielectric layer in the cathode formation section with a solid electrolyte layer; (v) covering at least a part of the solid electrolyte layer with a cathode lead-out layer; and (vi) after step (v), disposing a second insulating material in at least a part of a region of the separation section or impregnating the at least a part of the region of the separation section with the second insulating material, the region of the separation section being located closer to the anode section than the first insulating material, wherein: the method further comprising after step (ii) and before step (iv), forming a first groove by removing at least a part of the porous part in a region of the separation section, the region of the separation section being located closer to the anode section than the first insulating material, and in the step (vi), the second insulating material is disposed in at least a part of the first groove.
 9. The method according to claim 8, wherein in the step (vi), at least a part of a region of the porous part is impregnated with the second insulating material, the region of the porous part being located closer to the anode section than the first insulating material.
 10. A solid electrolytic capacitor comprising: a capacitor element including: an anode foil including a base material part and a porous part disposed on a surface of the base material part; a dielectric layer disposed on at least a part of a surface of the anode foil; a solid electrolyte layer covering at least a part of the dielectric layer; and a cathode lead-out layer covering at least a part of the solid electrolyte layer, wherein: the anode foil includes an anode section, a cathode formation section, and a separation section located between the anode section and the cathode formation section, the cathode formation section being covered with the solid electrolyte layer, the anode section being not covered with the solid electrolyte layer and other than the separation section, a first insulating material is disposed on a surface of the porous part in the separation section, at least a part of a first region of the porous part includes a second insulating material, the first region being located between the first insulating material and the base material part, and a third insulating material covers at least a part of the solid electrolyte layer between the first insulating material and an end of the cathode lead-out layer, the end of the cathode lead-out layer being at a side close to the anode section.
 11. The solid electrolytic capacitor according to claim 10, wherein the second insulating material is included in a second region of the porous part, the second region being located closer to the cathode formation section than the first insulating material.
 12. The solid electrolytic capacitor according to claim 10, wherein the second insulating material is included in a third region of the porous part, the third region being located closer to the anode section than the first insulating material.
 13. The solid electrolytic capacitor according to claim 10, wherein the second insulating material is included in the porous part in the cathode formation section.
 14. The solid electrolytic capacitor according to claim 10, wherein at least a part of the cathode lead-out layer includes the second insulating material.
 15. The solid electrolytic capacitor according to claim 10, wherein the third insulating material covers at least a part of the cathode lead-out layer.
 16. The solid electrolytic capacitor according to claim 10 comprising a laminated body in which a plurality of the capacitor elements are laminated, each of the plurality of the capacitor elements being the capacitor element, wherein an insulating material covers at least a part of a surface of the laminated body. 